In a vehicle having a substantially rigid underbody support structure, for example any number of interconnected longitudinal and/or lateral support beams, tubes, and/or rails of the type typically used in a pickup truck or other full-size vehicle frame, the vehicle may be prone to vertical vibration when driven in normal driving conditions. When a full size vehicle such as a pickup truck is driven on a typical residential street or is cruising at a relatively high rate of speed on highway pavement, the driver may perceive or experience this vertical vibration, also known as beaming shake, at the driver interface, such as the driver seat and steering column. Depending on the severity or the amplitude of oscillation, beaming shake may affect ride comfort, and in turn, the driver's overall perception of the vehicle.
The mass or weight of the vehicle and its cargo properly positioned or appended to the vehicle may help to reduce the amplitude of the beaming shake to some extent. However, as the reduction of vehicle weight is often an important vehicle design concern, simply adding additional weight or mass to the vehicle is usually a less than optimal solution. Conventionally, in order to free space within the truck bed or rear cargo area, a spare tire assembly in a full size truck is rigidly attached or fastened to the rear of the vehicle and under the support structure or frame. The spare tire assembly in this instance acts like a dead mass to the vehicle, with an imprecise affect on beaming shake.